I have a panel-mount voltmeter that I intend to install in the main cabin, right above the control panel. We used a DVM to check the voltages found a switch (water pump, I think) that has switched 12V power and ground.

I would connect an ammeter too, except that it would require running cables through the walls, which I'm not comfortable doing. I could mount one where the converter is, but it would require contortions to see it.

I have a panel-mount voltmeter that I intend to install in the main cabin, right above the control panel. We used a DVM to check the voltages found a switch (water pump, I think) that has switched 12V power and ground.

I would connect an ammeter too, except that it would require running cables through the walls, which I'm not comfortable doing. I could mount one where the converter is, but it would require contortions to see it.

K-R.

This is an excellent alternative and I see they've drop the price. I compared the accuracy with an in line amp meter and it was dead on.

We went to Lake Nacimiento, about a five-hour drive, for three days/two nights. The place had water, electricity and sewer, so we were on shore power the whole time.

The new converter took the whole two days to go to "idle" mode, with the charging voltage at 13.6 instead of the WFCO's 13.1. Two days after we got back the battery voltage was still 12.5. With the WFCO, the voltage was 11.8.

Here is a silly question. Make sure you have 12v coming into TT. I had been chasing a problem for a while of I had 13.2 coming out of TV but nothing going into TT. Finally traced 7-pin wires to a junction box underneath frame and there was a 30 amp fuse buried in that box- probably to keep from shorting out if trailer wire comes into contact with metal while camping- never though about it until now. Anyways, I changed out that hard to reach fuse with self resetting circuit breaker so I don't have to deal with it.

Glad it is all working out. If you find yourself doing a lot of boondocking, you should get a real battery monitor system that will help you understand what is going on with your batteries, your amp usage and your state of charge. Contrary to popular belief, a simple voltmeter IN USE tells you virtually nothing useful...other than that your battery is dead or charging.
Much written on this on the forum if you search for Victron or Trimetric.

If you don't boondock, you have no reason to monitor.

If you were measuring 13.6 charging voltage after two days...your charger was in ABSORBTION mode...not float. It should have dropped down to the 13.2 range which is the spec for float voltage on your unit. 13.6 is a long term battery killer if left plugged in. I suspect some significant battery loss of capacity. Suggest you leave it plugged in for 3 days to see if you can get it to drop down to float voltage eventually.

Oops! I should have made it a bit more clear. The charging voltage was 13.6 right after we plugged-in to shore power at the campground. I should have said that the little indicator light to settle down to "storage" mode, by the user manual.

I forgot to measure the voltage just before we unplugged to leave, when the light showed "storage" status.

I think a battery monitor makes sense. I would like to put one on the wall next to the main panel but that would involve running wires from the power converter bay. Our Surge-Guard panel is on the bedroom pedestal, which means we have to get on hands and knees to read it, so the monitor panel can go there, too.

Our power converter is located in a closed box under the bed. It felt a bit warmer than this old nerd feels comfortable about, so we're going to put a fan with a thermostatic switch to pull hot air out of the box. The WFCO cabinet where the new converter sits has some cooling slots, which the fan should draw through.

Ahhh...OK...that's better! LOL
Just FYI installing the Victron...the connection to the readout from the battery shunt below is a single telephone wire that plugs in just as you would one of those old fashoined phones grandpa used to use,
You can pretty much put the readout anywhere you can drop a wire.
Have fun!